A Coupled Multi-Electrode Array Sensor for Monitoring Galvanic Corrosion Between Copper and Steel

The advanced coupled multi-electrode array (CMEA) technique provides spatiotemporal insights into electrochemical processes. This study used the CMEA technique to monitor the distribution of anodic and cathodic activity during galvanic interactions between copper and steel. An important parameter influencing the intensity of galvanic corrosion is the anode-to-cathode area ratio, which was also investigated. After exposure, corrosion products were analyzed using microscopic and spectroscopic techniques, and the extent of actual corrosion damage was evaluated using µ -CT. In the CMEA sensor with a Cu:CS ratio of 24:1, the corrosion rate of the CS electrode was estimated at 0.86 mm year ⁻¹ . For the area ratio of Cu:CS 22:3, a lower corrosion rate of 0.56 mm year ⁻¹ was observed for the CS electrodes. The influence of the reduction process on copper electrodes and the intensity of galvanic corrosion is demonstrated. The main corrosion products on the CS electrodes were goethite, lepidocrocite, and akaganeite, indicating a corrosion process involving oxygen. The copper electrodes acted as cathodes, but some individual Cu electrodes also exhibited anodic activity. This suggests simultaneous anodic and cathodic activity, and the anodic activity was confirmed by Raman spectroscopy, which detected the presence of Cu ₂ O. Cu ₂ S was also detected, indicating corrosion processes involving bisulfide ions.